• Title/Summary/Keyword: fundamental ring

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Radial Variations in the Lengths of Wood Fibers and Vessel Elements in the Stem of Chestnut (Castanea crenata) Grown in Korea (국내산 밤나무 수간 내 목섬유 및 도관요소 길이의 방사방향 변이성)

  • Lee, Seon-Hwa;Kwon, Sung-Min;Lee, Sung-Jae;Febrianto, Fauzi;Kim, Nam-Hun
    • Journal of the Korean Wood Science and Technology
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    • v.38 no.6
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    • pp.490-497
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    • 2010
  • Radial variations in the lengths of wood fibers and vessel elements in the stem of chestnut (Castanea crenata) grown in Korea were investigated to get some fundamental information for efficient use of wood. Seven chestnut cultivars (Tanzawa, Ibuki, Arima, Ginyose, Tsukuba, Riheiguri, and Mansung) were examined in this study. The lengths of wood fibers and vessel elements were measured and analyzed by an optical microscope and an imaging analysis system. In all chestnut cultivars, the wood fiber length of latewood was longer than that of earlywood, and increased with the increase of growth ring number. Similarly, vessel element length of latewood was longer than that of earlywood, and showed increasing tendency with the increase of growth ring number. Consequently, it was considered that the lengths of wood fibers and vessel elements could be used for separating juvenile wood from adult wood in the chestnut stem.

Changes in Cellular Characteristics and Qualities of Matured and Juvenile Wood from Reforested Tree of Pinus koraiensis (잣나무 조림목(造林木)의 조직특성(組織特性)의 변동(變動)과 성열재(成熱材)·미성열재(未成熱材)의 재질(材質))

  • Kang, Sun-Koo
    • Journal of the Korean Wood Science and Technology
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    • v.21 no.2
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    • pp.73-80
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    • 1993
  • Pinus koraiensis is one of the most important reforestation species which had widely been planted around the country. Therefore, there are great research needs on the fundamental properties of wood to extend the frequency of uses and adequate availabilities. Research results on the characteristics of anatomical wood properties and changes are summarized as follows: 1. At a horizontal direction of tree trunk, the tracheid length at outer wood gradually becomes shorter as it reaches to pith. The tracheid length having between 32 and 42 annual rings showed over 2.5 times longer than that of pith, and also its length increases from the bottom to the top of the stem. 2. The tracheid diameters in latewood showed a little fluctuations, and the shortest near to the pith in earlywood. The tracheid diameters in earlywood are more than 2 times those of latewood, and the differences between the mature and juvenile wood in earlywood are less than 10${\mu}m$. 3. The tracheid wall thickness in early wood showed a little fluctuations. On the contrary, tracheid wall thickness in latewood rapidly increases from the pith to the bark. The tracheid wall of mature wood showed 10 to 20% thicker than that of juvenile wood. 4. The fibril angle at the secondary walls of tracheid within an annual ring showed higher degree in earlywood than that of latewood. The highest tracheid fibril angle was observed at around the pith of both earlywood and latewood. Then, fibril angle slowly decreased toward outer wood, and was stabilized after 15 years. 5. Structural boundaries between mature and juvenile wood from Pinus koraiensis are divided by 13 to 19 annual ring and distance of 5 to 8cm from the pith.

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Structural Behavior Analysis of Cap Shaped as an Arch for Suction-Installed Cofferdam (아치형 석션 가물막이 상판의 구조거동 분석)

  • Kim, Jeongsoo;Jeong, Youn-Ju;Park, Min-Su;Song, Sunghoon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.33 no.6
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    • pp.391-399
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    • 2020
  • In this study, the behaviors of a suction cap shaped as an arch were analyzed using finite element models. The fundamental structural behaviors of both flat- and arch-type caps were compared, and the advantages of the arch-shaped cap were explained. Moreover, the effects of geometric parameters and stiffener arrangements on the stress and deformation of the arch-shaped caps were investigated by comparisons of the changes in the behaviors of the caps. Additionally, the effects of boundary condition at the edge of the cap were analyzed to study the interactions between the cap and cofferdam walls; these results were used to derive the fundamental structural design of stiffened arch caps. Unlike flat caps, the results showed that ring stiffeners could improve the structural behaviors of arch caps remarkably, while the contributions of the radial stiffeners to the structural behaviors of the caps are dependent on constraints at the edges of the caps.

Effects of stiffening rings on the dynamic properties of hyperboloidal cooling towers

  • Zhang, Jun-Feng;Chen, Huai;Ge, Yao-Jun;Zhao, Lin;Ke, Shi-Tang
    • Structural Engineering and Mechanics
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    • v.49 no.5
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    • pp.619-629
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    • 2014
  • As hyperboloidal cooling towers (HCTs) growing larger and slender, they become more sensitive to gust wind. To improve the dynamic properties of HCTs and to improve the wind resistance capability, stiffening rings have been studied and applied. Although there have been some findings, the influence mechanism of stiffening rings on the dynamic properties is still not fully understood. Based on some fundamental perceptions on the dynamic properties of HCTs and free ring structures, a concept named "participation degree" of stiffening rings was proposed and the influence mechanism on the dynamic properties was illustrated. The "participation degree" is determined by the modal deform amplitude and latitude wave number of stiffening rings. Larger modal deform amplitude and more latitude waves can both result in higher participation degree and more improvement to eigenfrequencies. Also, this concept can explain and associate the pre-existing independent findings.

Ship Collision Avoidance Support Model in Close Quarters Situation (II) (근접상황 선박충돌회피지원모델에 관한 연구(II))

  • Yang Hyoung-Seon;Yea Byeong-Deok
    • Journal of Navigation and Port Research
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    • v.29 no.10 s.106
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    • pp.827-832
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    • 2005
  • In this paper, as a fundamental study of ship collision avoidance supporting system in close quarters situation, we propose ship collision avoidance support model for decreasing ship collision accidents those have occurred due to navigator's unsuitable maneuvering in close encounter. This model will effectively support maneuvering for collision avoidance through displaying the feasible area and the method of collision avoidance using own ship's turning characteristic about action of target ship's keeping course and velocity.

RESOLUTION OF UNMIXED BIPARTITE GRAPHS

  • Mohammadi, Fatemeh;Moradi, Somayeh
    • Bulletin of the Korean Mathematical Society
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    • v.52 no.3
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    • pp.977-986
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    • 2015
  • Let G be a graph on the vertex set $V(G)=\{x_1,{\cdots},x_n\}$ with the edge set E(G), and let $R=K[x_1,{\cdots},x_n]$ be the polynomial ring over a field K. Two monomial ideals are associated to G, the edge ideal I(G) generated by all monomials $x_i,x_j$ with $\{x_i,x_j\}{\in}E(G)$, and the vertex cover ideal $I_G$ generated by monomials ${\prod}_{x_i{\in}C}{^{x_i}}$ for all minimal vertex covers C of G. A minimal vertex cover of G is a subset $C{\subset}V(G)$ such that each edge has at least one vertex in C and no proper subset of C has the same property. Indeed, the vertex cover ideal of G is the Alexander dual of the edge ideal of G. In this paper, for an unmixed bipartite graph G we consider the lattice of vertex covers $L_G$ and we explicitly describe the minimal free resolution of the ideal associated to $L_G$ which is exactly the vertex cover ideal of G. Then we compute depth, projective dimension, regularity and extremal Betti numbers of R/I(G) in terms of the associated lattice.

The Historical Study of Korean Traditional Funtional Food (한국의 전통적 기능성 식품의 이용에 대한 역사적 고찰)

  • 한복진
    • Journal of the East Asian Society of Dietary Life
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    • v.6 no.2
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    • pp.235-255
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    • 1996
  • Natural substances, exploited in our daily life, have been applied to drugs to treat diseases and developed to functional foods by appropriate preparations, and these foods give beneficial effects on physical activities. In this paper, the utilization of traditional functional foods was studied with refer ring to old ancient writings published in the front-end of Chosun dynasty. The utilized vegetables were march mallow, turnip, radish, Chinese cabbage, lettuce, spinach, cucumber winter buds, flesh of a cabbage, eggplant, taro, burdock, Parsley, watershield plant, crown daisy, bamboo shoots, garlic, scallion, onion, acorn, bark of a tree, white goosefoot leaf, leaf of bean, pine mushroom, bracken. yam, mugwort, tea, ginseng, peppermint, fruit of the Maximowiczia chinensis, smartweed and pepper. The utilized fruits were chestnut, Chinese date, pine nuts, walnut, gingko nut, citrus. crab apple, pear, peach, grape, pomegranate, plum, Chinese quince, fig and watermelon. The utilized cereal were rice, barley, bean, buckweat and Job's-tears. The utilized sweetenings and seasonings were honey, wheat-gluten, sugar, oil, salt, soy sauce and vinegar. Our ancestors had a balanced diet using the various foods, and especially had a fundamental concept of "Foods have the efficacy of a remedy".edy".uot;.

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Methimazole-disulfide as an Anti-Thyroid Drug Metabolite Catalyzed the Highly Regioselective Conversion of Epoxides to Halohydrins with Elemental Halogens

  • Eshghi, H.;Tayyari, S.F.;Rezvani-Amin, Z.;Roohi, H.
    • Bulletin of the Korean Chemical Society
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    • v.29 no.1
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    • pp.51-56
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    • 2008
  • The regioselective ring opening of epoxides using elemental iodine and bromine in the presence of methimazole (MMI, a anti-thyroid drug) and its metabolite methimazole-disulfide as new catalysts are studied. MMI easily converted in vitro to MMI-disulfide without any double activation presented in vivo. FT-Raman and UV spectroscopies are used to study the interaction of iodine with these catalysts. The results indicate that both catalysts are efficient in polyiodide formation, but MMI-disulfide can catalyze this reaction in higher yield and regioselectivity. The complex [(MMI-disulfide)I]+.I3- is considered to be formed initially which could be bulkier by addition of excess of iodine in the course of the reaction. These bulky nucleophiles have a fundamental role in the high regioselectivity by attacking the less sterically hindered epoxide carbon. In this study we suggest that MMI is readily converted to MMI-disulfide by interaction with iodine or activated iodine in thyroid gland, and this process is responsible for high anti-thyroid activity of MMI.

Simultaneous Localization and Mobile Robot Navigation using a Sensor Network

  • Jin Tae-Seok;Bashimoto Hideki
    • International Journal of Fuzzy Logic and Intelligent Systems
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    • v.6 no.2
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    • pp.161-166
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    • 2006
  • Localization of mobile agent within a sensing network is a fundamental requirement for many applications, using networked navigating systems such as the sonar-sensing system or the visual-sensing system. To fully utilize the strengths of both the sonar and visual sensing systems, This paper describes a networked sensor-based navigation method in an indoor environment for an autonomous mobile robot which can navigate and avoid obstacle. In this method, the self-localization of the robot is done with a model-based vision system using networked sensors, and nonstop navigation is realized by a Kalman filter-based STSF(Space and Time Sensor Fusion) method. Stationary obstacles and moving obstacles are avoided with networked sensor data such as CCD camera and sonar ring. We will report on experiments in a hallway using the Pioneer-DX robot. In addition to that, the localization has inevitable uncertainties in the features and in the robot position estimation. Kalman filter scheme is used for the estimation of the mobile robot localization. And Extensive experiments with a robot and a sensor network confirm the validity of the approach.

Ship Collision Avoidance Support Model in Close Quarters Situation(II) (근접상황 선박충돌회피지원모델에 관한 연구(II))

  • Yang, Hyoung-Seon;Yea, Byeong-Deok
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • v.29 no.1
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    • pp.119-124
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    • 2005
  • In this paper, as a fundamental study of ship collision avoidance supporting system in close quarters situation, we propose ship collision avoidance support model for decreasing ship collision accidents those have occurred due to navigator's unsuitable maneuvering in close encounter. This model will effectively support maneuvering for collision avoidance through displaying the feasible area and the method of collision avoidance using own ship's turning characteristic about target ship's keeping course and velocity maneuvering actions.

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